CryptoAPITransform Class
Performs a cryptographic transformation of data. This class cannot be inherited.
Assembly: mscorlib (in mscorlib.dll)
| Name | Description | |
|---|---|---|
![]() | CanReuseTransform | Gets a value indicating whether the current transform can be reused. |
![]() | CanTransformMultipleBlocks | Gets a value indicating whether multiple blocks can be transformed. |
![]() | InputBlockSize | Gets the input block size. |
![]() | KeyHandle | Gets the key handle. |
![]() | OutputBlockSize | Gets the output block size. |
| Name | Description | |
|---|---|---|
![]() | Clear() | Releases all resources used by the CryptoAPITransform method. |
![]() | Dispose() | Releases all resources used by the current instance of the CryptoAPITransform class. |
![]() | Equals(Object) | Determines whether the specified object is equal to the current object.(Inherited from Object.) |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | Reset() | Resets the internal state of CryptoAPITransform so that it can be used again to do a different encryption or decryption. |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
![]() | TransformBlock(Byte(), Int32, Int32, Byte(), Int32) | Computes the transformation for the specified region of the input byte array and copies the resulting transformation to the specified region of the output byte array. |
![]() | TransformFinalBlock(Byte(), Int32, Int32) | Computes the transformation for the specified region of the specified byte array. |
The following code example demonstrates how to use members of the CryptoAPITransform class.
Imports System Imports System.Security.Cryptography Imports System.Collections Imports System.Text Public Class Form1 Inherits System.Windows.Forms.Form ' Use a public service provider for encryption and decryption. Dim desCSP As New DESCryptoServiceProvider ' Event handler for Run button. Private Sub Button1_Click( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click tbxOutput.Cursor = Cursors.WaitCursor tbxOutput.Text = "" Dim message As String = "01234567890123456789" Dim sourceBytes() As Byte = Encoding.ASCII.GetBytes(message) tbxOutput.AppendText("** Phrase to be encoded: " + message + vbCrLf) Dim encodedBytes() As Byte = EncodeBytes(sourceBytes) tbxOutput.AppendText("** Phrase after encoding: " + _ Encoding.ASCII.GetString(encodedBytes) + vbCrLf) Dim decodedBytes() As Byte = DecodeBytes(encodedBytes) tbxOutput.AppendText("** Phrase after decoding: " + _ Encoding.ASCII.GetString(decodedBytes) + vbCrLf) tbxOutput.AppendText(vbCrLf + "Sample ended successfully; " + _ "press Enter to continue.") tbxOutput.Cursor = Cursors.Default End Sub ' Encode the specified byte array by using CryptoAPITranform. Private Function EncodeBytes(ByVal sourceBytes() As Byte) As Byte() Dim currentPosition As Int16 = 0 Dim targetBytes(1024) As Byte Dim sourceByteLength As Integer = sourceBytes.Length ' Create a DES encryptor from this instance to perform encryption. Dim cryptoTransform As CryptoAPITransform cryptoTransform = CType(desCSP.CreateEncryptor(), CryptoAPITransform) ' Retrieve the block size to read the bytes. Dim inputBlockSize As Integer = cryptoTransform.InputBlockSize ' Retrieve the key handle. Dim keyHandle As IntPtr = cryptoTransform.KeyHandle ' Retrieve the block size to write the bytes. Dim outputBlockSize As Integer = cryptoTransform.OutputBlockSize Try ' Determine if multiple blocks can be transformed. If (cryptoTransform.CanTransformMultipleBlocks) Then Dim numBytesRead As Int16 = 0 While (sourceByteLength - currentPosition >= inputBlockSize) ' Transform the bytes from currentposition in the ' sourceBytes array, writing the bytes to the targetBytes ' array. numBytesRead = cryptoTransform.TransformBlock( _ sourceBytes, _ currentPosition, _ inputBlockSize, _ targetBytes, _ currentPosition) ' Advance the current position in the sourceBytes array. currentPosition += numBytesRead End While ' Transform the final block of bytes. Dim finalBytes() As Byte finalBytes = cryptoTransform.TransformFinalBlock( _ sourceBytes, _ currentPosition, _ sourceByteLength - currentPosition) ' Copy the contents of the finalBytes array to the targetBytes ' array. finalBytes.CopyTo(targetBytes, currentPosition) End If Catch ex As Exception tbxOutput.AppendText("Caught unexpected exception:" + _ ex.ToString() + vbCrLf) End Try ' Determine if the current transform can be reused. If (Not cryptoTransform.CanReuseTransform) Then ' Free up any used resources. cryptoTransform.Clear() End If ' Trim the extra bytes in the array that were not used. Return TrimArray(targetBytes) End Function ' Decode the specified byte array using CryptoAPITranform. Private Function DecodeBytes(ByVal sourceBytes() As Byte) As Byte() Dim currentPosition As Int16 = 0 Dim targetBytes(1024) As Byte Dim sourceByteLength As Integer = sourceBytes.Length ' Create a DES decryptor from this instance to perform decryption. Dim cryptoTransform As CryptoAPITransform cryptoTransform = CType(desCSP.CreateDecryptor(), CryptoAPITransform) Dim inputBlockSize As Integer = cryptoTransform.InputBlockSize Try ' Determine if multiple blocks can be transformed. If (cryptoTransform.CanTransformMultipleBlocks) Then Dim numBytesRead As Int16 = 0 While (sourceByteLength - currentPosition >= inputBlockSize) ' Transform the bytes from currentPosition in the ' sourceBytes array, writing the bytes to the targetBytes ' array. numBytesRead = cryptoTransform.TransformBlock( _ sourceBytes, _ currentPosition, _ inputBlockSize, _ targetBytes, _ currentPosition) ' Advance the current position in the source array. currentPosition += numBytesRead End While ' Transform the final block of bytes. Dim finalBytes() As Byte finalBytes = cryptoTransform.TransformFinalBlock( _ sourceBytes, _ currentPosition, _ sourceByteLength - currentPosition) ' Copy the contents of the finalBytes array to the targetBytes ' array. finalBytes.CopyTo(targetBytes, currentPosition) End If Catch ex As Exception tbxOutput.AppendText("Caught unexpected exception:" + _ ex.ToString() + vbCrLf) End Try ' Strip out the second block of bytes. Array.Copy(targetBytes, (inputBlockSize * 2), targetBytes, inputBlockSize, targetBytes.Length - (inputBlockSize * 2)) ' Trim the extra bytes in the array that were not used. Return TrimArray(targetBytes) End Function ' Resize the dimensions of the array to a size that contains only valid ' bytes. Private Function TrimArray(ByVal targetArray() As Byte) As Byte() Dim enum1 As IEnumerator = targetArray.GetEnumerator() Dim i As Int16 = 0 While (enum1.MoveNext()) If (enum1.Current.ToString().Equals("0")) Then Exit While End If i += 1 End While ' Create a new array with the number of valid bytes. Dim returnedArray(i - 1) As Byte For j As Int16 = 0 To i - 1 Step 1 returnedArray(j) = targetArray(j) Next Return returnedArray End Function ' Event handler for Exit button. Private Sub Button2_Click( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button2.Click Application.Exit() End Sub #Region " Windows Form Designer generated code " Public Sub New() MyBase.New() 'This call is required by the Windows Form Designer. InitializeComponent() 'Add any initialization after the InitializeComponent() call End Sub 'Form overrides dispose to clean up the component list. Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean) If disposing Then If Not (components Is Nothing) Then components.Dispose() End If End If MyBase.Dispose(disposing) End Sub 'Required by the Windows Form Designer Private components As System.ComponentModel.IContainer 'NOTE: The following procedure is required by the Windows Form Designer 'It can be modified using the Windows Form Designer. 'Do not modify it using the code editor. Friend WithEvents Panel2 As System.Windows.Forms.Panel Friend WithEvents Panel1 As System.Windows.Forms.Panel Friend WithEvents Button1 As System.Windows.Forms.Button Friend WithEvents Button2 As System.Windows.Forms.Button Friend WithEvents tbxOutput As System.Windows.Forms.RichTextBox <System.Diagnostics.DebuggerStepThrough()> _ Private Sub InitializeComponent() Me.Panel2 = New System.Windows.Forms.Panel Me.Button1 = New System.Windows.Forms.Button Me.Button2 = New System.Windows.Forms.Button Me.Panel1 = New System.Windows.Forms.Panel Me.tbxOutput = New System.Windows.Forms.RichTextBox Me.Panel2.SuspendLayout() Me.Panel1.SuspendLayout() Me.SuspendLayout() ' 'Panel2 ' Me.Panel2.Controls.Add(Me.Button1) Me.Panel2.Controls.Add(Me.Button2) Me.Panel2.Dock = System.Windows.Forms.DockStyle.Bottom Me.Panel2.DockPadding.All = 20 Me.Panel2.Location = New System.Drawing.Point(0, 320) Me.Panel2.Name = "Panel2" Me.Panel2.Size = New System.Drawing.Size(616, 64) Me.Panel2.TabIndex = 1 ' 'Button1 ' Me.Button1.Dock = System.Windows.Forms.DockStyle.Right Me.Button1.Font = New System.Drawing.Font( _ "Microsoft Sans Serif", _ 9.0!, _ System.Drawing.FontStyle.Regular, _ System.Drawing.GraphicsUnit.Point, _ CType(0, Byte)) Me.Button1.Location = New System.Drawing.Point(446, 20) Me.Button1.Name = "Button1" Me.Button1.Size = New System.Drawing.Size(75, 24) Me.Button1.TabIndex = 2 Me.Button1.Text = "&Run" ' 'Button2 ' Me.Button2.Dock = System.Windows.Forms.DockStyle.Right Me.Button2.Font = New System.Drawing.Font( _ "Microsoft Sans Serif", _ 9.0!, _ System.Drawing.FontStyle.Regular, _ System.Drawing.GraphicsUnit.Point, _ CType(0, Byte)) Me.Button2.Location = New System.Drawing.Point(521, 20) Me.Button2.Name = "Button2" Me.Button2.Size = New System.Drawing.Size(75, 24) Me.Button2.TabIndex = 3 Me.Button2.Text = "E&xit" ' 'Panel1 ' Me.Panel1.Controls.Add(Me.tbxOutput) Me.Panel1.Dock = System.Windows.Forms.DockStyle.Fill Me.Panel1.DockPadding.All = 20 Me.Panel1.Location = New System.Drawing.Point(0, 0) Me.Panel1.Name = "Panel1" Me.Panel1.Size = New System.Drawing.Size(616, 320) Me.Panel1.TabIndex = 2 ' 'tbxOutput ' Me.tbxOutput.AccessibleDescription = _ "Displays output from application." Me.tbxOutput.AccessibleName = "Output textbox." Me.tbxOutput.Dock = System.Windows.Forms.DockStyle.Fill Me.tbxOutput.Location = New System.Drawing.Point(20, 20) Me.tbxOutput.Name = "tbxOutput" Me.tbxOutput.Size = New System.Drawing.Size(576, 280) Me.tbxOutput.TabIndex = 1 Me.tbxOutput.Text = "Click the Run button to run the application." ' 'Form1 ' Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15) Me.ClientSize = New System.Drawing.Size(616, 384) Me.Controls.Add(Me.Panel1) Me.Controls.Add(Me.Panel2) Me.Name = "Form1" Me.Text = "CryptoAPITransform" Me.Panel2.ResumeLayout(False) Me.Panel1.ResumeLayout(False) Me.ResumeLayout(False) End Sub #End Region End Class ' ' This sample produces the following output: ' ' ** Phrase to be encoded: 01234567890123456789 ' ** Phrase after encoding: Eaa0$\iv\oXgS ' ** Phrase after decoding: 01234567890123456789 ' ' Sample ended successfully; press Enter to continue.
Available since 1.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

